Uniaxial tensile clamp for concrete thin plate test piece and automatic centering and clamping method

Abstract

The invention discloses a concrete sheet test piece uniaxial tensile fixture and an automatic centering clamping method, and the concrete sheet test piece uniaxial tensile fixture comprises a group of U-shaped frames, two groups of connecting cylinders which fixedly penetrate through the two sides of the U-shaped frames respectively and are arranged oppositely, two groups of sliding discs which are arranged on the inner sides of the U-shaped frames in a reverse synchronous sliding manner and are respectively arranged on the two groups of connecting cylinders in a sleeving manner, and two groups of inserting columns which are arranged oppositely and oppositely. The sliding sleeves are respectively sleeved in the two groups of connecting cylinders in a sliding manner and penetrate out of one ends, positioned on the inner side of the U-shaped frame, of the connecting cylinders; the device has the beneficial effects that the two groups of circular chucks are matched with the two groups of deviation rectifying rods, so that the device can gradually clamp a test piece through the two groups of deviation rectifying rods after the two groups of circular chucks clamp the concrete test piece, the posture of the test piece is corrected, and the two groups of circular chucks continuously clamp the test piece in the posture adjusting process of the test piece; therefore, the test piece is polished between the two groups of circular chucks, and the situation that the centering effect is reduced due to burrs on the surface of the concrete test piece can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of clamps, and in particular to a uniaxial tensile clamp for a concrete thin plate specimen and an automatic centering clamping method. Background Art

[0002] The concrete tensile test is a test method that applies a tensile load to the concrete for a period of time, causing it to deform in the axial direction until it fails. By measuring the load and deformation, parameters such as the tensile strength, elastic modulus and Poisson's ratio of the concrete can be obtained.

[0003] In the uniaxial tensile test of concrete, the specimen needs to be clamped on both sides by a fixture for loading. To ensure the accuracy of the test results, the specimen must be strictly aligned so that its axis is completely consistent with the loading direction. If the alignment is poor, the thin plate specimen is prone to buckling or twisting deformation due to the additional bending moment during the tensile process, resulting in serious distortion of the test data and even the inability to obtain valid tensile performance parameters.

[0004] Currently, laboratories generally use the traditional method of directly clamping the two ends of the specimen with wedge-shaped or hydraulic clamps. On the one hand, this clamping method requires the operator to manually adjust the centering, which requires a high level of operator experience and technical skills. On the other hand, due to the lack of a precise centering control mechanism, it is often difficult to ensure the ideal centering effect in actual experiments, thus affecting the experimental accuracy.

[0005] Therefore, a uniaxial tensile fixture for concrete thin plate specimens and an automatic centering clamping method are proposed. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] The present invention has been proposed in view of the above-mentioned problems.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a uniaxial tensile fixture for a concrete thin plate specimen, comprising:

[0009] A set of pennant crosses;

[0010] Two sets of connecting tubes are fixedly installed on both sides of the U-shaped frame and are arranged opposite each other;

[0011] Two sets of sliding discs are arranged to slide synchronously in opposite directions on the inner side of the U-shaped frame and are respectively sleeved on the two sets of connecting cylinders;

[0012] Two groups of plug-in columns are respectively slidably sleeved in the two groups of connecting tubes and pass through one end of the connecting tube located on the inner side of the U-shaped frame;

[0013] Two sets of circular chucks are arranged to slide synchronously in opposite directions between the two sets of connecting cylinders and are respectively fixed to the ends of the two sets of plug-in columns;

[0014] Two groups of springs are respectively arranged between the two groups of sliding plates and adjacent chuck plates, with both ends fixedly connected to the sliding plates and chuck plates respectively;

[0015] Two groups of connecting sleeves are respectively rotatably sleeved on the two groups of connecting cylinders and are respectively rotatably connected to the sides of the two groups of sliding discs facing away from the chuck discs;

[0016] Two sets of correcting rods are L-shaped and fixedly connected to the two sets of connecting sleeves respectively and are centrally symmetrically arranged, with the rod bodies away from the connecting sleeves being perpendicular to the disc surface of the circular chuck;

[0017] Two sets of driving blocks are respectively fixed on the inner sides of the two sets of connecting sleeves;

[0018] Two sets of driving grooves are respectively provided on the outer surfaces of the two sets of connecting cylinders for the sliding of the driving blocks, and are composed of a horizontal groove body and an inclined groove body, and the inclined groove bodies of the two sets of driving grooves are inclined in opposite directions;

[0019] A set of hydraulic cylinders, fixedly connected to one side of the C-shaped frame, with piston rods slidingly passing through the C-shaped frame and ends fixedly connected to adjacent sliding plates;

[0020] When the two sets of sliding plates approach each other, the two sets of circular chucks are driven to approach each other by the two sets of springs, and the two sets of driving blocks respectively move from the horizontal groove body of the corresponding driving groove to the inclined groove body:

[0021] When the two groups of driving blocks slide along the corresponding horizontal grooves, the two groups of correcting rods remain open, and the two groups of circular chucks approach each other;

[0022] When the two groups of driving blocks slide along the corresponding inclined grooves, the two groups of circular chucks clamp the test piece, and the two groups of correcting rods rotate around the axial direction of the connecting tube to clamp the correcting test piece.

[0023] As a preferred solution of the uniaxial tensile fixture for concrete thin plate specimens described in the present invention, the two groups of sliding plates are fixedly connected to the outer sides of the second columns, the two groups of second racks are fixedly connected to the sides facing each other, the two groups of second racks are arranged parallel to each other and are slidably connected to the U-shaped frame, the inner top of the U-shaped frame is rotatably connected to the first gear, the two sides of the first gear are respectively engaged with the two groups of second racks, and the two groups of sliding plates move synchronously in opposite directions through the first gear and the two groups of second racks.

[0024] As a preferred solution of the uniaxial tensile fixture for concrete thin plate specimens described in the present invention, the two groups of circular chucks are fixedly connected to a connecting ring on the opposite side, the outer sides of the two groups of connecting rings are fixedly connected to a first column, the sides of the two groups of first columns facing each other are fixedly connected to a first rack, the two groups of first racks are slidably connected to the U-shaped frame and are arranged parallel to each other, a second gear is engaged between the two groups of first racks, the second gear is arranged to rotate coaxially with the first gear, and the two groups of circular chucks move synchronously in opposite directions through the second gear and the two groups of first racks.

[0025] As a preferred solution of the uniaxial tensile fixture for concrete thin plate specimens described in the present invention, two groups of double-track guide rails arranged parallel to each other are fixedly connected to the top of the C-shaped frame, the two groups of the side facing away from the tooth surface are fixedly connected to the second slider, the two groups of the first racks are fixedly connected to the side facing away from the tooth surface with the first slider, the two groups of the second sliders and the two groups of the first sliders are respectively slidably connected to the two groups of double-track guide rails, the two groups of the first racks are slidably connected to the C-shaped frame through the two groups of the first sliders and the two groups of the double-track guide rails, and the two groups of the second racks are slidably connected to the C-shaped frame through the two groups of the second sliders and the two groups of the double-track guide rails.

[0026] As a preferred solution of the uniaxial tensile fixture for concrete thin plate specimens described in the present invention, the surfaces of the two sets of circular clamps facing each other are both rough and are provided with grid-shaped grooves.

[0027] As a preferred solution of the uniaxial tensile fixture for concrete thin plate specimens described in the present invention, when the two groups of driving blocks are located in the corresponding horizontal troughs, the two groups of correcting rods are located on the horizontal symmetric plane of the circular clamp.

[0028] As a preferred solution of the uniaxial tensile fixture for concrete thin plate specimens described in the present invention, the arc of the inclined groove body of the driving groove around the surface of the connecting tube is greater than or equal to 90°, and the transition section between the horizontal groove body and the inclined groove body is arc-shaped.

[0029] As a preferred solution of the uniaxial tensile fixture for concrete thin plate specimens described in the present invention, it further includes a threaded barrel and a screw rod, the threaded barrel is fixedly connected to one side of the U-shaped frame and is arranged opposite to the connecting barrel, the screw rod thread passes through the threaded barrel and extends into the corresponding connecting barrel, and the length of the screw rod is greater than the length of the connecting barrel.

[0030] As a preferred solution of the uniaxial tensile fixture for concrete thin plate specimens described in the present invention, the screw is in a "T" shape.

[0031] The present invention further provides a method for automatically centering and clamping a concrete thin plate specimen, comprising the following steps:

[0032] S1, set up two sets of clamps symmetrically in the upper and lower parts, and place the two ends of the concrete thin plate specimen between the two sets of circular clamping plates of the two sets of clamps;

[0033] S2, start the hydraulic cylinder, the hydraulic cylinder pushes the corresponding sliding plate, the sliding plate pushes the corresponding circular chuck through the spring when it moves, the sliding plate and the circular chuck move, drive another set of sliding plates and the circular chuck to move synchronously, the two sets of circular chucks approach each other, and finally the two sets of circular chucks clamp the test piece, the sliding plate moves and drives the corresponding connecting sleeve to move synchronously, the connecting sleeve drives the driving block to slide along the driving groove, before the two sets of circular chucks clamp the test piece, the driving block is located in the horizontal groove body, after the two sets of circular chucks clamp the test piece, the two sets of driving blocks move between them into the inclined groove body;

[0034] S3, when the two sets of driving blocks move into the inclined slot body, they continue to move and drive the corresponding connecting sleeves to rotate. The two sets of connecting sleeves rotate in opposite directions. The two sets of connecting sleeves gradually clamp the specimen and adjust the specimen posture. Finally, the two sets of connecting sleeves clamp the specimen. The connecting sleeves of the two sets of fixtures work together to center the specimen.

[0035] S4, rotate the screw until it presses against the corresponding plug-in column to complete the specimen clamping.

[0036] The beneficial effects of the present invention are as follows: by arranging two sets of circular chucks in cooperation with two sets of correcting rods, the device can gradually clamp the specimen through the two sets of correcting rods after the two sets of circular chucks clamp the concrete specimen, thereby correcting the specimen posture. During the specimen posture adjustment process, the two sets of circular chucks continuously clamp the specimen, so that the specimen is polished between the two sets of circular chucks, which can avoid the decrease in centering effect due to burrs on the surface of the concrete specimen. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0038] Figure 1 This is a schematic diagram of the lower three-dimensional structure of a uniaxial tensile fixture for a concrete thin plate specimen of the present invention.

[0039] Figure 2 This is a partial three-dimensional structural schematic diagram of a uniaxial tensile fixture for a concrete thin plate specimen according to the present invention.

[0040] Figure 3 The figure is a partial cross-sectional structural schematic diagram of a uniaxial tensile fixture for a concrete thin plate specimen according to the present invention.

[0041] Figure 4This is a schematic diagram of the partially disassembled structure of a uniaxial tensile fixture for a concrete thin plate specimen according to the present invention.

[0042] Figure 5 This is a schematic diagram of the three-dimensional structure of the correction rod part of the uniaxial tension fixture of a concrete thin plate specimen of the present invention.

[0043] Figure 6 This is a schematic diagram of the use of a uniaxial tensile fixture for concrete thin plate specimens according to the present invention.

[0044] Description of the drawings: 1. U-shaped frame; 2. Connecting cylinder; 3. Circular chuck; 4. Plug-in column; 5. Sliding plate; 6. Spring; 7. Hydraulic cylinder; 8. Connecting ring; 9. Threaded cylinder; 10. First column; 11. Double-track guide rail; 12. First rack; 13. Connecting sleeve; 14. First slider; 15. Screw; 16. Second column; 17. Second rack; 18. Second slider; 19. First gear; 20. Second gear; 21. Correction rod; 22. Drive block. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0046] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0047] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0048] Furthermore, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, when describing the embodiments of the present invention, cross-sectional views illustrating device structures may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, the three-dimensional dimensions of length, width, and depth should be included.

[0049] Example 1

[0050] like Figure 1-Figure 5 As shown, a uniaxial tensile fixture for a concrete thin plate specimen comprises:

[0051] A set of pendant 1;

[0052] Two sets of connecting tubes 2 are fixedly installed on both sides of the U-shaped frame 1 and are arranged opposite each other;

[0053] Two sets of sliding plates 5 are arranged to slide synchronously in opposite directions on the inner side of the U-shaped frame 1 and are respectively sleeved on the two sets of connecting cylinders 2;

[0054] Two groups of plug-in posts 4 are respectively slidably sleeved in the two groups of connecting tubes 2 and pass through one end of the connecting tubes 2 located on the inner side of the U-shaped frame 1;

[0055] Two sets of circular chucks 3 are arranged to slide synchronously in opposite directions between the two sets of connecting cylinders 2 and are respectively fixed to the ends of the two sets of plug-in columns 4;

[0056] Two groups of springs 6 are respectively arranged between the two groups of sliding plates 5 and the adjacent chuck plates 3, with both ends fixedly connected to the sliding plates 5 and the chuck plates 3 respectively;

[0057] Two sets of connecting sleeves 13 are respectively rotatably sleeved on the two sets of connecting cylinders 2 and are respectively rotatably connected to the sides of the two sets of sliding discs 5 facing away from the circular chuck 3;

[0058] Two sets of correcting rods 21 are L-shaped and fixedly connected to the two sets of connecting sleeves 13 respectively and are centrally symmetrically arranged. The rod bodies away from the connecting sleeves 13 are perpendicular to the disc surface of the circular chuck 3.

[0059] Two sets of driving blocks 22 are fixed on the inner sides of the two sets of connecting sleeves 13 respectively;

[0060] Two sets of driving grooves are respectively provided on the outer surfaces of the two sets of connecting cylinders 2 for the sliding of the driving blocks 22. The driving grooves are composed of a horizontal groove body and an inclined groove body. The inclined groove bodies of the two sets of driving grooves are inclined in opposite directions.

[0061] A set of hydraulic cylinders 7, fixedly connected to one side of the C-shaped frame 1, with the piston rods slidingly passing through the C-shaped frame 1 and the ends fixedly connected to the adjacent sliding plates 5;

[0062] When the two sets of sliding plates 5 approach each other, the two sets of circular chucks 3 are driven to approach each other by the two sets of springs 6, and the two sets of driving blocks 22 respectively move from the horizontal groove body of the corresponding driving groove to the inclined groove body:

[0063] When the two sets of driving blocks 22 slide along the corresponding horizontal grooves, the two sets of correcting rods 21 remain open, and the two sets of circular chucks 3 approach each other. In this process, the spring 6 mainly plays the role of transmitting between the sliding plate 5 and the circular chuck 3;

[0064] When the two sets of driving blocks 22 slide along the corresponding inclined grooves, the two sets of circular clamps 3 clamp the test piece, and the two sets of correcting rods 21 rotate around the axial direction of the connecting tube 2 to clamp the corrected test piece. In this process, the spring 6 is gradually compressed to provide space for the relative displacement of the sliding plate 5 and the circular clamp 3. At the same time, the clamping force of the two sets of circular clamps 3 on the test piece gradually increases.

[0065] like Figures 1-4 As shown, the outer sides of the two sets of sliding plates 5 are fixedly connected to the second columns 16, and the sides of the two sets of second columns 16 facing each other are fixedly connected to the second racks 17. The two sets of second racks 17 are arranged parallel to each other and are slidably connected to the U-shaped frame 1. The inner top of the U-shaped frame 1 is rotatably connected to the first gear 19. The two sides of the first gear 19 are respectively engaged with the two sets of second racks 17. The two sets of sliding plates 5 move synchronously in opposite directions through the first gear 19 and the two sets of second racks 17.

[0066] like Figures 1-4 As shown, the two groups of circular chucks 3 are fixedly connected to the opposite side with a connecting ring 8, the outer sides of the two groups of connecting rings 8 are fixedly connected to the first column 10, and the sides of the two groups of first columns 10 facing each other are fixedly connected to the first rack 12. The two groups of first racks 12 are slidably connected to the U-shaped frame 1 and are arranged parallel to each other. A second gear 20 is engaged between the two groups of first racks 12. The second gear 20 and the first gear 19 are coaxially rotated. The two groups of circular chucks 3 move synchronously in opposite directions through the second gear 20 and the two groups of first racks 12.

[0067] like Figure 1-Figure 3 As shown, two groups of double-track guide rails 11 arranged parallel to each other are fixedly connected to the top of the C-shaped frame 1, and the second slider 18 is fixedly connected to the side of the two groups facing away from the tooth surface. The first slider 14 is fixedly connected to the side of the two groups of first racks 12 facing away from the tooth surface. The two groups of second sliders 18 and the two groups of first sliders 14 are respectively slidably connected to the two groups of double-track guide rails 11. The two groups of first racks 12 are slidably connected to the C-shaped frame 1 through the two groups of first sliders 14 and the two groups of double-track guide rails 11. The two groups of second racks 17 are slidably connected to the C-shaped frame 1 through the two groups of second sliders 18 and the two groups of double-track guide rails 11.

[0068] like Figure 1 、 Figure 2 and Figure 4 As shown, the surfaces of the two sets of circular chucks 3 facing each other are rough, and both are provided with grid-shaped grooves. The rough surface of the circular chucks 3 here is to increase the friction of the circular chucks 3. When the two sets of circular chucks 3 clamp the specimen and the two sets of correction rods 21 correct the angle of the specimen, the two sets of circular chucks 3 have a certain grinding effect on the specimen, which can grind off the irregular burrs on the surface of the concrete specimen, further improving the clamping effect and centering accuracy. The grid-shaped grooves here are to accommodate the debris generated during grinding, to prevent the debris from staying between the specimen and the circular chuck 3, thereby avoiding affecting the centering accuracy and clamping effect.

[0069] like Figure 1-Figure 3As shown, when the two sets of driving blocks 22 are located in the corresponding horizontal slots, the two sets of correcting rods 21 are located on the horizontal symmetric plane of the circular chuck 3. In this state, the opening angle of the two sets of correcting rods 21 is the largest, thereby improving the applicability of the device.

[0070] like Figure 4 As shown, the arc of the inclined groove body of the driving groove around the surface of the connecting tube 2 is greater than or equal to 90°. When the two sets of correcting rods 21 are located on the horizontal symmetry plane of the circular clamping disk 3, the angle between the two correcting rods 21 is 90°. At this time, if the two correcting rods 21 are to be closed, the two correcting rods 21 should be rotated 90°. Therefore, the arc of the inclined groove body of the driving groove around the surface of the connecting tube 2 is greater than or equal to 90° to ensure that the two correcting rods 21 can correct the test pieces of any width, thereby further improving the applicability of the device. The transition section between the horizontal groove body and the inclined groove body is arc-shaped. The arc-shaped transition section here is to enable the driving block to smoothly transition between the horizontal groove body and the inclined groove body.

[0071] like Figure 3 As shown, it also includes a threaded barrel 9 and a screw 15. The threaded barrel 9 is fixedly connected to one side of the U-shaped frame 1 and is arranged opposite to the connecting barrel 2. The screw 15 is threaded through the threaded barrel 9 and extends into the corresponding connecting barrel 2. The length of the screw 15 is greater than the length of the connecting barrel 2. The screw 15 here is to further tighten and fix the two sets of circular splints 3 after the centering is completed to ensure the clamping effect. The threaded barrel 9 and the screw 15 structure here can be replaced with hydraulic parts or cylinders and other components.

[0072] like Figure 1 and Figure 2 As shown, the screw rod 15 is in a “T” shape, and the “T” shape is used to facilitate the rotation of the screw rod 15 .

[0073] Example 2

[0074] A method for automatically centering and clamping a concrete thin plate specimen, using the clamp in Example 1, comprises the following steps:

[0075] S1, set up two sets of clamps symmetrically in the upper and lower parts, and place the two ends of the concrete thin plate specimen between the two sets of circular clamping plates 3 of the two sets of clamps respectively;

[0076] S2, start the hydraulic cylinder 7, which pushes the corresponding sliding plate 5. When the sliding plate 5 moves, the corresponding circular chuck 3 is pushed by the spring 6. When the sliding plate 5 and the circular chuck 3 move, they drive another set of sliding plates 5 and the circular chuck 3 to move synchronously. The two sets of circular chucks 3 approach each other. Finally, the two sets of circular chucks 3 clamp the test piece. When the sliding plate 5 moves, it drives the corresponding connecting sleeve 13 to move synchronously. The connecting sleeve 13 drives the driving block 22 to slide along the driving groove. Before the two sets of circular chucks 3 clamp the test piece, the driving block 22 is located in the horizontal groove body. After the two sets of circular chucks 3 clamp the test piece, the two sets of driving blocks 22 move between them into the inclined groove body.

[0077] S3, when the two sets of driving blocks 22 move into the inclined slot body, they continue to move and drive the corresponding connecting sleeves 13 to rotate. The two sets of connecting sleeves 13 rotate in opposite directions. The two sets of connecting sleeves 13 gradually clamp the specimen and adjust the specimen posture. Finally, the two sets of connecting sleeves 13 clamp the specimen. The connecting sleeves 13 of the two sets of fixtures work together to center the specimen.

[0078] S4, rotating the screw rod 15 so that the screw rod 15 is pressed against the corresponding plug-in column 4, thus completing the clamping of the test piece.

[0079] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A uniaxial tensile fixture for concrete thin plate specimens, characterized in that: include: A set of pennant crosses; Two sets of connecting tubes are fixedly installed on both sides of the U-shaped frame and are arranged opposite each other; Two sets of sliding discs are arranged to slide synchronously in opposite directions on the inner side of the U-shaped frame and are respectively sleeved on the two sets of connecting cylinders; Two groups of plug-in columns are respectively slidably sleeved in the two groups of connecting tubes and pass through one end of the connecting tube located on the inner side of the U-shaped frame; Two sets of circular chucks are arranged to slide synchronously in opposite directions between the two sets of connecting cylinders and are respectively fixed to the ends of the two sets of plug-in columns; Two groups of springs are respectively arranged between the two groups of sliding plates and adjacent chuck plates, with both ends fixedly connected to the sliding plates and chuck plates respectively; Two groups of connecting sleeves are respectively rotatably sleeved on the two groups of connecting cylinders and are respectively rotatably connected to the sides of the two groups of sliding discs facing away from the chuck discs; Two sets of correcting rods are L-shaped and fixedly connected to the two sets of connecting sleeves respectively and are centrally symmetrically arranged, with the rod bodies away from the connecting sleeves being perpendicular to the surface of the circular chuck; Two sets of driving blocks are respectively fixed on the inner sides of the two sets of connecting sleeves; Two sets of driving grooves are respectively provided on the outer surfaces of the two sets of connecting cylinders for the sliding of the driving blocks, and are composed of a horizontal groove body and an inclined groove body, and the inclined groove bodies of the two sets of driving grooves are inclined in opposite directions; A set of hydraulic cylinders, fixedly connected to one side of the C-shaped frame, with piston rods slidingly passing through the C-shaped frame and ends fixedly connected to adjacent sliding plates; When the two sets of sliding plates approach each other, the two sets of circular chucks are driven to approach each other by the two sets of springs, and the two sets of driving blocks respectively move from the horizontal groove body of the corresponding driving groove to the inclined groove body: When the two groups of driving blocks slide along the corresponding horizontal grooves, the two groups of correcting rods remain open, and the two groups of circular chucks approach each other; When the two groups of driving blocks slide along the corresponding inclined grooves, the two groups of circular chucks clamp the test piece, and the two groups of correcting rods rotate around the axial direction of the connecting tube to clamp the correcting test piece.

2. The uniaxial tensile fixture for concrete thin plate specimens according to claim 1, characterized in that: The outer sides of the two groups of sliding plates are fixedly connected to the second columns, and the sides of the two groups of second columns facing each other are fixedly connected to the second racks. The two groups of second racks are arranged parallel to each other and are slidably connected to the U-shaped frame. The inner top of the U-shaped frame is rotatably connected to the first gear, and the two sides of the first gear are respectively engaged with the two groups of second racks. The two groups of sliding plates move synchronously in opposite directions through the first gear and the two groups of second racks.

3. The uniaxial tension fixture for concrete thin plate specimens according to claim 2, characterized in that: The two groups of circular chucks are fixedly connected to a connecting ring on the opposite side of each other, and the outer sides of the two groups of connecting rings are fixedly connected to a first column, and the sides of the two groups of first columns facing each other are fixedly connected to a first rack, and the two groups of first racks are slidably connected to the U-shaped frame and are arranged parallel to each other. A second gear is engaged between the two groups of first racks, and the second gear is arranged to rotate coaxially with the first gear. The two groups of circular chucks move synchronously in opposite directions through the second gear and the two groups of first racks.

4. The uniaxial tensile fixture for concrete thin plate specimens according to claim 3, characterized in that: Two groups of double-track guide rails arranged parallel to each other are fixedly connected to the top of the C-shaped frame, and the sides of the two groups facing away from the tooth surface are fixedly connected to the second slider, and the sides of the two groups of first racks facing away from the tooth surface are fixedly connected to the first slider, and the two groups of second sliders and the two groups of first sliders are respectively slidably connected to the two groups of double-track guide rails, and the two groups of first racks are slidably connected to the C-shaped frame through the two groups of first sliders and the two groups of double-track guide rails, and the two groups of second racks are slidably connected to the C-shaped frame through the two groups of second sliders and the two groups of double-track guide rails.

5. The uniaxial tension fixture for concrete thin plate specimens according to claim 1, characterized in that: The surfaces of the two groups of circular chucks facing each other are both rough and are provided with grid-shaped grooves.

6. The uniaxial tension fixture for concrete thin plate specimens according to claim 1, characterized in that: When the two groups of driving blocks are located in the corresponding horizontal slots, the two groups of correcting rods are located on the horizontal symmetric plane of the circular chuck.

7. The uniaxial tension fixture for concrete thin plate specimens according to claim 6, characterized in that: The arc angle of the inclined groove body of the driving groove around the surface of the connecting cylinder is greater than or equal to 90 degrees, and the transition section between the horizontal groove body and the inclined groove body is in an arc shape.

8. The uniaxial tension fixture for concrete thin plate specimens according to claim 1, characterized in that: It also includes a threaded barrel and a screw, wherein the threaded barrel is fixedly connected to one side of the U-shaped frame and is arranged opposite to the connecting barrel. The screw thread passes through the threaded barrel and extends into the corresponding connecting barrel. The length of the screw is greater than the length of the connecting barrel.

9. The uniaxial tension fixture for concrete thin plate specimens according to claim 8, characterized in that: The screw is in a "T" shape.

10. A method for automatically centering and clamping a concrete thin plate specimen, using the uniaxial tension fixture for concrete thin plate specimens according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, set up two sets of clamps symmetrically in the upper and lower parts, and place the two ends of the concrete thin plate specimen between the two sets of circular clamping plates of the two sets of clamps; S2, start the hydraulic cylinder, the hydraulic cylinder pushes the corresponding sliding plate, the sliding plate pushes the corresponding circular chuck through the spring when it moves, the sliding plate and the circular chuck move, drive another set of sliding plates and the circular chuck to move synchronously, the two sets of circular chucks approach each other, and finally the two sets of circular chucks clamp the test piece, the sliding plate moves and drives the corresponding connecting sleeve to move synchronously, the connecting sleeve drives the driving block to slide along the driving groove, before the two sets of circular chucks clamp the test piece, the driving block is located in the horizontal groove body, after the two sets of circular chucks clamp the test piece, the two sets of driving blocks move between them into the inclined groove body; S3, when the two sets of driving blocks move into the inclined slot body, they continue to move and drive the corresponding connecting sleeves to rotate. The two sets of connecting sleeves rotate in opposite directions. The two sets of connecting sleeves gradually clamp the specimen and adjust the specimen posture. Finally, the two sets of connecting sleeves clamp the specimen. The connecting sleeves of the two sets of fixtures work together to center the specimen. S4, rotate the screw until it presses against the corresponding plug-in column to complete the specimen clamping.

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